Technical Field
The present invention relates to a method for fabricating semiconductor packages.
Description of Related Art
Semiconductor industries continue to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continually reducing minimum feature size, which allows more components to be integrated into a given area. These smaller electronic components require smaller packages that utilize less area than packages of the past, in some applications.
Wafer level package (WLP) technique is an advanced packaging technology, by which a die is manufactured and tested on a wafer, and then the wafer is singulated by dicing for assembly in a surface-mount line. Because the WLP technique utilizes the whole wafer as one object, not utilizing a single chip or die, therefore, before performing a scribing process, packaging and testing has been accomplished; furthermore, WLP is such an advanced technique so that the process of wire bonding, die mounting and under-filling can be omitted. By utilizing WLP techniques, the cost and manufacturing time can be reduced, and the resulting structure of WLP can be equal to the die; therefore, this technique can meet the demands of miniaturization of electronic devices.
Though the advantages of the WLP technique are mentioned above, some issues still exist that influence the acceptance of WLP technique. For instance, one type of WLP technique that has been recently developed is Integrated Fan-Out Wafer-Level Packaging (InFO-WLP), in which the coefficient of thermal expansion CTE difference (mismatching) between the materials of a structure of WLP and the motherboard becomes another critical factor to the mechanical instability of the structure. Another type of WLP technique is chip-on-wafer-on-substrate (CoWoS), in which the wafer may be too thin to handle in the packaging process, and a temporary bonding process is needed, which brings additional problems such as residue adhesives or extra cost and manufacturing time.